Endosome regulated retinal homeostasis and disease

项目摘要/摘要 视杆感光细胞功能和活性的丧失是视网膜色素变性病因学的核心 (Rp)，影响1/4,000。我们的实验室对了解内小体的作用有长期的兴趣 在光感受器的膜运输中，关于外节的许多知识已经被了解 蛋白质靶向。相比之下，我们对错误的蛋白质是如何降解的知之甚少， 以及产生不可降解废物的后果(S)。新出现的研究表明 内切溶酶体系统是阿尔茨海默氏症等多种神经系统疾病的遗传热点 帕金森氏症，其病理是由初级神经元病变和持续的 小胶质细胞炎症。在过去的资助期间，我们生成了一个特定于杆子的小鼠品系 删除VPS35。早期内体蛋白VPS35是集中控制几个 相互关联的贩运路径。VPS35基因与阿尔茨海默氏症和 我们的结果表明，在这些突变的小鼠中，几种外节蛋白是 定位错误，并经历了蛋白质降解。令人惊讶的是，VPS35有缺陷的杆端 积累了大量的脂膜废物，被周围的小胶质细胞吞噬， 然后迁移到视网膜下空间。后者表达的分子特征是 阿尔茨海默病小鼠模型中发现的与疾病相关的小胶质细胞。鞘磷脂的水平，这是 一直与突触膜的完整性和神经炎症有关，也是异常的 在突变小鼠中升高。这里的首要目标是检验一个中心假设，即 富含鞘磷脂的杆状废物中的一部分会激活小胶质细胞，导致几种功能缺陷。 (如吞噬、清除)和炎症。我们将从机制上研究 鞘脂(Aim1)和小胶质细胞(AIM2)使用跨学科和最先进的贡献 技术(例如，脂质组学、转录组学、3D电子显微镜、多抗原流式细胞术) 无论是在体内还是体外。我们还将讨论抑制这些途径中的任何一个是否可以抵消 持续的小胶质细胞炎症，进而改善视网膜病理。拟议的研究将 提供对视网膜动态平衡的基本理解的敏锐见解 光感受器-小胶质细胞串扰。它们有很高的潜力导致治疗RP的新策略 可能还有其他病因重叠的神经系统疾病。

Project Summary/Abstract Loss of function and viability of rod photoreceptors is central to the etiology of retinitis pigmentosa (RP) which affects 1 in ~4,000. Our lab has a long-term interest in understanding the endosome's role in membrane trafficking of photoreceptors and much has been learned about the outer segment protein targeting. In contrast, we know very little about how the mistrafficked proteins are degraded, and the consequence(s) of the generation of non-degradable wastes. Emerging studies showed the endo-lysosomal system is a genetic hot spot for several neurological diseases such as Alzheimer's and Parkinson's, whose pathology is contributed by both the primary neuronal lesions and sustained microglial inflammation. During the past grant period, we generated a mouse line with rod-specific deletion of VPS35. The early endosomal protein VPS35 is the hub that centrally controls several interconnected trafficking pathways. VPS35 has been genetically linked to Alzheimer's and Parkinson’s. Our results showed that in these mutant mice several outer segment proteins were mislocalized and underwent proteolytic degradation. Strikingly, VPS35 deficient rod terminals accumulated massive lipid-membrane wastes, which were engulfed by the surrounding microglia, which then migrated away to the subretinal space. The latter expressed the molecular signatures of disease-associated microglia identified in Alzheimer's mouse models. The level of sphingolipid, which has been connected to synaptic membrane integrity and neural inflammation, was also abnormally elevated in mutant mice. The overarching goal here is to test a central hypothesis that the engulfment of the rod-derived sphingolipid-rich wastes activates microglia, leading to several functional deficits (e.g., phagocytosis, clearance) and inflammation. We will mechanistically investigate the pathological contribution by sphingolipids (Aim1) and microglia (Aim2) using interdisciplinary and state-of-the-art techniques (e.g., lipidomics, transcriptomes, 3D electron microscopy, multi-antigen flow cytometry) both in vivo and in vitro. We will also address whether inhibiting any of these pathways can offset the sustained microglial inflammation, and in turn, ameliorate retinal pathology. The proposed studies will provide keen insights into the fundamental understanding of the retina homeostasis harnessed by the photoreceptor-microglia crosstalk. They have a high potential to lead to new strategies for treating RP and potentially other neurological diseases with overlapping etiologies.